"gallery" display order with wp_get_attachment_image

Hello everybody,
is there a way to sort attachments to a post similar to the gallery tab that shows the images connected to a post?

I want to change the order in the “gallery” tab and the query below should change the order of the posted attachments accordingly.

this is the code I am using:

<?php
  $CP =  $post->ID
?>
<?php query_posts('p=' . $CP . ''); ?>
<?php if ( have_posts() ) : while ( have_posts() ) : the_post();    

 $args = array(
   'post_type' => 'attachment',
   'numberposts' => -1,
   'orderby'       => 'name',
   'post_status' => null,
   'post_parent' => $post->ID
  );

  $attachments = get_posts( $args );
     if ( $attachments ) {
        foreach ( $attachments as $attachment ) {
			echo '<li><p>';
           	echo wp_get_attachment_image( $attachment->ID, array(746,500) );
			echo '</p></li>';
          }
     }

 endwhile; endif; ?>

I know there is no such thing as:
'orderby' => 'gallery order',
but I hope you understand what I am searching for.