My colleague John Schmitt and former colleague Heather Boushey looked at this issue a couple of years ago. They noted that there was a far larger dispersion in the wages of men with college degrees than was the case with women. In fact, there was a substantial overlap between the distribution of wages of men without college degrees and men with college degrees.
The ev-psych story is that men tend to have wider variance in general. They dominate both the best jobs and the worst jobs. College may not affect this.
Pointer from Mark Thoma.