I have the same hair "problem" (it runs in the family on my mother's side), I'm early 30s as well with significant gray hair showing and refusing to dye my hair, and... for me it has always been pretty much an advantage to get senior / management positions relatively fast since I was about 25 (I always tell anyone who asks/mocks about my hair that "at least they take me more seriously") and it has worked out pretty well so far.

My resume never goes back more than 5-7 yrs because it's not meant to be a history report but should be a strong 1-pager with just the highlights of your career, relative and relevant to the position you're applying for (for example, I started leaving out my education because it's not relevant to my experience anymore and it's not been a problem at all). I hope, for my own sake, that I don't owe everything to my hair, but it's definitely not been an obstacle to my progress.

I think confidence and attitude signal more than whatever you think people think about your hair (for starters, stop worrying/thinking about what other people may or may not perceive about you, simply project the self that you want to be) and if you worry about the gap in age perception so much, why not just put your birth date on your resume?