Hi @feliciah7 - The best way to solve this will depend on if the family has been modeled as native Revit, or is just a nested DWG file loaded into the Revit family. If it has been modeled as a Revit family there are a couple of different ways to color this within a Render:
1) Add a material control onto the modelled elements within the Family editor, if this is set up as an instance then this can be controlled per instance within the project environment. To do this, select the geometry within the family editor and within the properties palette select the material option, linking a parameter through.
2) When in the project environment, all items on a specific phase can be assigned a material. To do this, set all required objects onto a Phase, and within the phase filters tool on the palette can set a material to the whole phase.
I hope this helps, L.