I use PaintShopPro. You can open the pages with the Moon crescents then use the Lasso select tool to outline the crescent so just that area will be affected by any editing you do.
You can then goto
Adjust>Hue and Saturation>Colorize and play with the sliders to get the crescents to the shade of green you want.
There are most likely similar controls in other graphics programs like PhotoShop
Here is an example:
