Hi Bob.
Where there is a mix of colours it’s just to show the root note. For scales and modes, the black notes are the root note. For the blues scales, black is the root, blue dots are the ‘blues’ notes.
Arpeggios show the root note in red.
In hindsight I should have kept with a consistent colour. The reason they aren’t consistent is because over the years I have used different diagram creating software. They all started off done by hand in drawing software 🙂