rewrite URL based on selected taxonomy for post page

I have a taxonomy called "group", and their values like "red", "blue", "green" (these are generating dynamic" no any fixed group value.

during post publish I am selecting "Group" for each post. 1 group for each post.

I want to add a rewrite URL for the post if the taxonomy is "red" or "blue" or "green" then the URL of that post should come like

"myweb.com/red/post-slug-name" or "myweb.com/green/post-slug-name" or "myweb.com/blue/post-slug-name"

add_action( 'init', 'create_group_tax' ); function create_group_tax() {     register_taxonomy(              'group',              'post',               array( 'label' => 'Group',                      'hierarchical' => true                 )         ); }  add_rewrite_rule('^red/([^/]*)/?','index.php?group=$  matches[1]','top'); 

also, I want to make it regex rule "'^red/([^/]*)/?'" dynamic with selected taxonomy,this time just to make a test i added it as a static string.

result : Page not found. Nothing here – http://localhost/wordpress/red/my-test/

what do you suggest to do this?