This photo comes from the book Last Team Standing about the Phil-Pitt 'Steagles.'
An excerpt from the book concerning the Giants game states..."As he (RB Jack Hinkle) stood searching for a crack in the onrushing blue wall, Hinkle thought about how good it would feel to show Steve Owen just what he was missing. Then Hinkle dropped the ball. He barely managed to recover his fumble, collapsing on the ball on the six-yard line an instant before the blue wall came crashing down."
This indicates the Giants were in blue jerseys that night.