Simple (palette-based) picker:

• Access key + s Focuses the simple selector

Keyboard legend

• enter, down (when popup is closed) opens the popup
• left arrow selects previous color
• right arrow selects next color

 

• up/down move one row up/down
• enter select current color
• escape cancel the selection

HSV picker:

• Access key + h Focuses the HSV selector

Keyboard legend

• enter, down (when popup is closed) opens the popup
• arrows update saturation/value in the big rectangle
• ctrl + left/right update hue slider
• ctrl + up/down update opacity slider (when opacity present)

 

• shift hold shift for fine-tuning
• enter select current color
• escape cancel the selection