Some interesting history on Green One here.
The Green One
It would seem that even by the mid-1950s, airways had started to be identified on charts just by the first letter of their colour (so "G1" rather than "Green One"), and presumably in the same way on flightplans, etc, though I certainly recall airways clearance readbacks, for example, quoting "White Nine, Amber One", etc in the 60s.
So the change from "Green" to "Golf", when it came, wouldn't have resulted in any change to airways charts, though of course it would have been apparent on R/T.