Go to 'product item color settings' part
All color: your product has any colors it will be show all colors
Only colors available: Only show variant not out of stock
Set name the color and select the color code you want to customize.
For simple color: you can choose 1 or 2 color (pink, white, gray, black...)
For complex color: you can upload image and do not select color. (remember enable 'color image')
Hopr you success!!