Coloring Segments

Hello, I am fairly new to 3D slicer and wanted to know if I could use different colors to highlight the nerves in my project:

I made the whole brain as one segment, so I am unable to just change the color of the specific lobes/nerves I want to change different colors. Is it possible to use, for example, the paint brush tool (or something similar) to manually highlight the sections I want in a different color than the green that the entire brain is in?

Thanks in advance!

Please read the Segmentation section of SLicer User manual Image Segmentation — 3D Slicer documentation

and SlicerMorph segmentation tutorial Tutorials/Segmentation/ at main · SlicerMorph/Tutorials · GitHub