Change Texture on atlas map to new color or whole new material?

Hello there,

Based on the images I have upload I have highlighted 2 wall-sets I need other colors (and more to come). I have also uploaded an image on the type of walls I am talking about. Will I have to create a whole new material everytime I change the color (trying to save room on the maps for road/stone/etc. I just feel like the same texture repeatedly with a different color seems like a waste of room. But would this be the case? Just trying to avoid more draw calls than needed.