ColorPaint is a standalone script (for SU2016 and above) which is part of FredoTools. It implements a configurable Color Selector, independent from models and persistent across SketchUp sessions and SketchUp versions.
ColorPaint includes a large range of color palettes to which you can add your own.
ColorPaint is part of FredoTools, which is distributed on Sketchucation. More info here.
ColorPaint is available for Sketchup 2016 and above.
Here are 2 videos explaining how ColorPaint works.