Another great old Laurence Fellows illustration. Or perhaps by Leslie Saalburg? In any case, most young guys don't need to look quite this elegant in 2014, but that doesn't mean you shouldn't make a solid effort to look pulled together once you leave college or university and enter the real world.
I'd suggest the following as a bare minimum with plenty of room for possible later expansion or diversion, depending on your own goals, company culture, and the type of work you'll be doing. Here we go:
*1 wool sports jacket. . . 2 in slightly different patterns are even better!
*1 navy blazer
*1 charcoal, mid-gray, or navy two-piece wool suit
*2 pairs of better khakis that keep a crease (Bill's or similar)
*2 pairs of creased wool dress pants in charcoal, navy, gray, or taupe for instance
*1 pair of dark dress jeans (without rips or fading) that actually fit.
*1 pair of lace-up brown leather dress shoes (with leather soles) and a brown belt to match
*1 pair of same in black. . .
*1 pair of cordovan/oxblood penny loafers with matching belt
*7 long-sleeved cotton dress shirts, mostly in light blue or white, with precise neck and arm dimensions. Stick with button-down collars to start since these look great even sans a necktie.
*5-6 traditional, fairly conservative neckties (repp stripes, foulards, etc.)
*7 pairs of to-the-knee dress socks -- In navy and charcoal. Save the wilder statement socks for later.
*7 white t-shirts
*14 pairs of underwear -- If you're an adult, you should have two weeks worth at least!
Now, this amount of clothes and undergarments might seem excessive as a starter wardrobe, bit I'd be willing to bet that lots of young, college-aged guys already own many of these items, at least in part. With the notable exception of t-shirts, socks, and underwear, which, to be perfectly frank, should only be purchased brand spanking new (Eeeew!!!), you can add missing items by visiting thrift/charity shops where you can usually find decent quality stuff that has lots of life left in it for almost nothing, or by perusing physical stores and/or websites of establishments like Brooks Brothers, L.L. Bean, and Land's End, for example, and keeping an eye out for sales and seasonal clearances. However you beef up your wardrobe though, do spend the money to have any necessary alterations made to your clothes before you wear them for the first time, as I've mention before here at The Average Guy's Guide to Classic Style, so that you look your best.
Keep in mind too that you might be able to skip the suit given the woefully informal nature of many workplaces in 2014, although it is my firm opinion that every guy ought to have at least one clean suit in his closet that actually fits and is in a good state of repair for the occasional formal event like weddings, funerals, special dinners, job interviews, and meeting that special someone's parents for the first time.
Of course, if working part-time in the local cafe until your early 30s is part of the plan once you graduate from college, then, of course jeans, a hooded sweatshirt, and the ubiquitous knit ski cap, or "beanie" in current parlance, along with the requisite five-day beard will do just fine. Knock yourself out.
Otherwise, I'd advise that you add the above items to your wardrobe gradually, but have most of them by at least the end of your first 6-12 months out of school. . . Unless you live in a very warm part of the world, or the expected standard of dress in your particular field is extremely casual.
Finally, even if your company has an "everyday is casual Friday" ethos, with neither suits nor ties required. . . ever, I'd still suggest wearing a sports jacket or blazer over a long-sleeved dress shirt most days. It's a good look and helps even very young guys appear a bit more pulled together, focused, capable, and in charge of their particular duties and responsibilities rather than resembling one more doofus-slob intern, who has trouble sorting the mail, taking lunch orders, and fixing copier jams. Just my two cents on the matter.