Display a colour of custom taxonomy on the page

The colours are associated to the individual terms, so the process is to get the terms for the current post, then load and display the field for each term.

$terms = get_the_terms( get_the_ID(), 'colour' );
if( $terms && ! is_wp_error( $terms ) ){
    foreach( $terms as $term ){
        // show color code
        echo get_field( 'colour_acf', 'colour_' . $term->term_id );
        // or insert color code into background-color of a div
        echo '<div style="background-color:' . get_field( 'colour_acf', 'colour_' . $term->term_id ) . '">&nbsp;</div>';
    }
}