I used to have a mod that retextured nuka cola quantums to be brighter, but can't find it on the nexus anymore.

Does anyone know where I can find this mod?

Are you sure it's not just the HDR setting in the display options? That makes a huge difference in how Quantum looks.

Try the Nuka Cola Theme 3000 file from http://www.fallout3nexus.com/downloads/file.php?id=12978. If that's not it, it might have been http://www.fallout3nexus.com/downloads/file.php?id=5814 which includes Skykappa's textures.