It's all look pretty much like CelShading Toon Shading (you can google both and how it works.) with flat colours. In Arnold you have basically there a slot for Diffuse Flat Colors and can readjust color of the Shade that works something like on the screenshot. Shade color also can be connected to the diffuse color with…
Looks pretty good! The pointy deltoids look a little strange. The figure seems to have a lot of surface sinks (the infraspinatus area in pic 2 for example) which look odd.