OK, as a guy, I'll throw in a different perspective. I'm going to be 41 in less than two months. I definitely have a few strands of gray but honestly, I have no intention of coloring it. I don't care if it's gray. I just care if it's there. I'll take a head of gray hair full of curls.
However, since I notice a ton of gray hair on my face I go with the clean shaven look to look younger. Most people are surprised when I tell them my age.