Over the years several aviation artists have produced beautiful depictions of what the
Robertson DH-4 mail planes must have looked like in 1926-27  -  in action and in color!
Ray Crane Art
Bob Benjamin Art
Tron Bykle Art
Mike Machat Art
(click on pictures to enlarge)

Note:  In addition to the four examples shown here, I've also seen an original painting in the Missouri Historical Society of one of Lindbergh's emergency parachute jumps from a CAM-2 DH-4.  The painting shows Lindbergh descending in his parachute and looking back at the red and silver DH-4 that appears to be coming right towards him (just like in the movie "THE SPIRIT OF ST. LOUIS" starring James Stewart).  Unfortunately, I don't have a photo of the Missouri Historical Society painting, nor do I know the artist's name.