It seems that Humphrey was an Ivy League guy, being a member of Dartmouth College's class of 1914. He then was at New York's Art Students League to complete his training under Frank DuMond. After that, he had a successful career as an illustrator and mural painter for the next quarter century or so. However, his career after the early 1940s is essentially a mystery to me for now, though he is known to have taught.
Humphrey's style was hard-edge, something of a necessity for mural work. Yet he was able to ease off ever so slightly, resulting in works that are not overly stark and held together well.
I'm guessing this was made around 1920, but can't be sure because the subject is historical, not contemporary, so I can't use dress for estimation purposes.
A blurred image, but I include it to show that Humphrey did hit the illustration Big Time.
Humphrey was one of the early cover artists for Liberty magazine.
Ever loyal, Humphrey hints that this scene has to do with a Dartmouth College football game (note the Dartmouth green uniform and the letter "D" on the girl's pennant).
A useful background link to a Dartmouth Review article on the mural (controversial, especially for those practicing political correctness) is here.