Don't know if the velvet would be white? I'd assume it might be, but all antlers are white under the velvet when they first shed. The color in antlers comes from rubbing them on trees and brush as well as the ground. Once an albino buck starts rubiing it's antlers they should look the same as other deer in the area.
Hopefully the picture took here is a albino buck I took this year!! It was on public ground!! I wish it was on private ground were it could of grown up but it won't of made it. It would of been poached if it made it through the season!! Nocalhonker