Xodo: Annotation Color Picker
Tap on the border-color/fill color/color/text color in the annotation Style Picker dialog.
There are three color pickers: Standard Color Palette, Custom Color Palette, and an HSV Color Picker Board. You can switch between them by swiping left and right.
1. HSV Color Picker Board:
2. Standard Color Palette:
3. Custom Color Palette: