Whilst reading up on her I also found another few works by her that feature redheads. This first is called Aurora Triumphans and in it the central figure appears to have bright red hair. Aurora, the naked figure on the right is symbolic of day (or dawn), the dark shrouded figure on the left is symbolic of night.
This final painting is called The Worship of Mammon. It's quite a vivid illustration of the love of money, and shows a red-haired woman in purplish-pink drapery.