Galland F-4 was also in autumn 1940 in grey colors.... so
Sorry mate, but the Bf 109 F-4 was built from May 1941 (by WNF) onwards and then by Erla (from June 1941 onwards). First F-4 had WNr 7001. Messerschmitt GmbH built no F-4 at all...
In Autumn 1940, Galland's Bf 109 F was most probably an F-1 from Mtt GmbH (WNr 5621-5757).
Jicehem