There is a black & white photo of Adolf Galland's E-4 rudder on page 41 of the Squadron/Signal Messerschmitt Bf 109 In Action, Part 1. This clearly shows that the upper and lower portions were yellow and the center section, behind the 40 kill markings, as being light blue.
Just an item of additional interest --- Galland was a heavy cigar smoker and he had his ground crew install a cigar lighter somewhere in the cockpit of this aircraft. Galland claimed to have the only cigar lighter equipped 109 in the Luftwaffe.
Pete