Theme Colour Palette - add to functions.php

// Theme colour palette
function xyz_setup_theme_supported_features() {
	add_theme_support( 'editor-color-palette', array(
		array(
			'name' => __( 'Navy', 'xyz' ),
			'slug' => 'navy',
			'color' => '#032f3c',
		),
		array(
			'name' => __( 'Orange', 'xyz' ),
			'slug' => 'orange',
			'color' => '#fd8204',
		),
		array(
			'name' => __( 'Green', 'xyz' ),
			'slug' => 'green',
			'color' => '#b8bf0d',
		),
		array(
			'name' => __( 'Magenta', 'xyz' ),
			'slug' => 'magenta',
			'color' => '#e60088',
		),
		array(
			'name' => __( 'Purple', 'xyz' ),
			'slug' => 'purple',
			'color' => '#87319a',
		),

		array(
			'name' => __( 'Red', 'xyz' ),
			'slug' => 'red',
			'color' => '#e01f1d',
		),

		array(
			'name' => __( 'Cyan', 'xyz' ),
			'slug' => 'cyan',
			'color' => '#00aeef',
		),

		array(
			'name' => __( 'Light Green', 'xyz' ),
			'slug' => 'light-green',
			'color' => '#03783d',
		),

		array(
			'name' => __( 'Blue', 'xyz' ),
			'slug' => 'blue',
			'color' => '#0032a0',
		),
		array(
			'name' => __( 'White', 'xyz' ),
			'slug' => 'white',
			'color' => '#fff',
		),
	) );
}
add_action( 'after_setup_theme', 'xyz_setup_theme_supported_features' );

// Disable custom colours
add_theme_support( 'disable-custom-colors' );