Just for some extra inspiration, here is the color theme used by ordel.se:
There is no colorblind option, the default mode is already colorblind-friendly (at least for my particular colorblindness). This has the advantage that you eliminate confusion when discussing the game and sharing your results.
Not sure if these particular colors will look good on the goban, but since only two different colors are needed I certainly think it should be possible to find a theme that both looks good and is distinguishable for everybody 