Switch the Admin Color Scheme for a user on various multisite subsites

functions.php

/**
 * Force Admin Color Scheme on admin pages for a user account based on the site we're on.
 * Valid admin_color values include:
 * 	- fresh (Default)
 * 	- light
 * 	- modern
 * 	- blue
 * 	- coffee
 * 	- ectoplasm
 * 	- midnight
 * 	- ocean
 * 	- sunrise
 */
add_action( 'admin_init', 'update_admin_color_scheme' );
function update_admin_color_scheme() {
	$current_site = get_current_blog_id();
	$current_user = get_current_user_id();
	if ( 2 == $current_user ) { // this is the user ID we want to change the admin color scheme for
		switch ( $current_site ) {
			// first site to change the color scheme for
			case '16': 
				$color = array( 'ID' => $current_user, 'admin_color' => 'blue' );
				break;
			// second site to change the color scheme for
			case '14': 
				$color = array( 'ID' => $current_user, 'admin_color' => 'coffee' );
				break;
			// All other sites.
			default:
				$color = array( 'ID' => $current_user, 'admin_color' => 'fresh' );
				break;
		}
	}

	wp_update_user( $color );

}