A nice example of this is shown in Figure 2 of the paper "Illustrative Rendering in Team Fortress 2" [1] from Valve. It shows how they tried to make the silhouettes of each character class distinct and readable. (And the paper also discusses the choices that went into the color palette.)
[1] https://steamcdn-a.akamaihd.net/apps/valve/2007/NPAR07_Illus...