Spray it with Feibings Leather Sheen Acrylic spray or Hi~Sheen srpay.
2-3 light coats will work nicely. (Don't to heavy coats otherwise it will make a candy coating and crack when the leather is bent)
Looks awesome! You can also blend the acrylics together to get a fading effect for shadows and highlights.
To me, this piece feels more like a very traditional gesture study. If I were coloring it, I'd do a diluted tan or yellow and antique it to look like old parchment.