This filter allows you to set the default color palettes inside your color pickers in the Customizer.
This filter requires an array in the return.
You should return 8 colors.
add_filter( 'generate_default_color_palettes', 'tu_custom_color_palettes' );
function tu_custom_color_palettes( $palettes ) {
$palettes = array(
'#000000',
'#FFFFFF',
'#F1C40F',
'#E74C3C',
'#1ABC9C',
'#1e72bd',
'#8E44AD',
'#00CC77',
);
return $palettes;
}