I would recommend not coloring your beard. It's not good for your beard, and the upkeep is endless. Embrace the coloring. There is nothing wrong with gray or white hairs. Why would you consider having some grey hairs as prematurely aging yourself? You're as old as you feel. Don't sweat it so much, just enjoy the beard (if your job even let's you keep it.) Good luck to you.

There are two kinds of people in this world that go around beardless, boys and women, and I am neither one.

   Jayson