I have a material with 8 different colors and my object has 8 different vertex groups. All of the vertex groups have assigned locations on the mesh (robot head). How can I make it so the "HeadWhite" labeled vertex group is colored white (node-labeled), the "HeadLightGrey" labeled vertex group is colored light grey (node-labeled), and so on, within the same material?
EDIT: I'm using diffuse shaders in the picture below as an example, which I placed there for people to test. Once this is answered, I'm going to replace the diffuse shaders with multiple textures and other shaders, so I can't use something like Vertex Colors to do the job.

