functions.php

add_action( 'woocommerce_display_product_attributes', 'woo_custom_variation_display', 12 );

function woo_custom_variation_display( $product_attributes ) {
   global $product;
   // make sure this is a variable product. If not, return
   if ( ! $product->is_type( 'variable' ) ) return;

   if ( isset( $product_attributes[ 'attribute_pa_color' ] ) ) {

   $variations = $product->get_available_variations( 'object' );
   
   //empty array to add the pa_color names to
  $variations_to_display_ar = array();
   

  // make sure there are some variations
  if( ! empty( $variations ) ) {
      foreach ( $variations as $key => $variation ) {
         foreach ( $variation->attributes as $at_key => $value ) {
            // only interested in the pa_color values
            if ( 'pa_color' == $at_key ) {
               // adding an uppercase version (because they are stored lowercase) of each color value to our array
               array_push( $variations_to_display_ar, ucwords( $value ) );
            }
         }
      }

      /* need to keep only unique values as the product can have multiple variations of same color. ie blue hoodie with logo, blue hoodie without logo etc */
      $variations_display_string = implode( ', ', array_unique( $variations_to_display_ar ) );

      //set the attribute_pa_color value to the string of enabled variation colors
      $product_attributes[ 'attribute_pa_color' ][ 'value' ]  = $variations_display_string;

      return $product_attributes;
      }
   }
}