Instructions
Select "Customize Avatar" from the My Xbox screen.
Open "Change My Features." A list of facial features appear.
Keep the cursor over the "Hairstyles" box in the top right corner for roughly 1 minute.
Wait until the cursor above the "Hairstyles" box spins around (see Tips.) Quickly press "A." A screen appears with 9 extra hair colors for your avatar in addition to the existing collection.