This was done in black and white films too, of course.
You painted them green.
In 1939, being a spinster was a horrifying fate for many women, who relied on marriage for money and protection. Those who went uncoupled were often depicted as devastatingly unhappy, shrewish, and miserable. And I'm sure some were.
Women's Suffrage became law, nationally, in the US, in 1919.
Women riding bikes being a sign of rebellion was from 1900.
Context is EVERYTHING.
She's ALREADY a witch.
She's awful, inhuman, grotesque. And she's no soft, desaturated, Boris Karloff green, she's TRAFFIC LIGHT green. It was a SHOCK. This would be a LOT of moviegoers' first time seeing ANYTHING like this.
2019 you is making inaccurate, hair-trigger assumptions by cherry-picking certain features and ignoring others.
1939 you would have been screaming "OH JESUS CHRIST, SHE'S GREEN!"
y e a h .
The intent is clear. Couldn't be clearer.