Use themes

Right click title bar -> Options.. -> Looks, drag and drop local theme files to Theme edit box, apply or save.

Theme files:

https://github.com/geoffstokes/base16-mintty

https://github.com/oumu/mintty-color-schemes

https://github.com/mavnn/mintty-colors-solarized

https://github.com/PhilipDaniels/mintty/tree/master/themes