Home teams wear dark colors.. visiting team, light colors.
This is an NCAA rule.
This may be changed in a per game basis if both teams agree in advance in writing.
Recently they modified the rule to allow BOTH teams to wear home colors provided that both teams' colors contrast sufficiently. I THINK this was changed after some backlash when the NCAA didn't allow USC and UCLA to bring back the tradition of both teams wearing home colors (which they used to do from the 1920's - 1980' when the home/away uniform rule was created)