White hair

I am 40 years old and have been "growing" grey since age 25. I am now fully white haired, with locks and loving it. My question is not to reverse it but to ask what it is I can do to get the hairline (front) to be gray as it is still black in some spots and I don`t want it to be black and to find out how I can keep the grey colour bright. Any suggestions would be welcomed.
Thank you