I checked the original files and the ships are not layered, so the coloured part is not separate. It's possible through photoshop to extract the coloured parts and save them separately. But this loses some of the subtle detail in the coloured sections, so the result doesn't look as good as the hue shift mechanism I mentioned in my earlier reply.
If you're familiar with photoshop (though I assume most graphics software packages offer something similar), you'd be recreating the 'hue/saturation' effect, in Krita it's called 'HSV/HSL Adjustment'. See attached image.