Here is a separation that id like to share. It was a challenging one as it is an actual painting.
Most of the colors seemed to be in the same range of reds and browns, so i needed to manually cut masks in order to keep the flesh colors and browns away from the reds.
base white
grey
blue
green
brown + dark brown
flesh + light flesh
red + dark red
yellow
highlight white
black
Here is .gif showing the masks and sequence of the colors going down:
