Changing the colours used to be very time consuming.
Each of the model files have a set of large list of .dds files which correspond to different parts. Basically I use photoshop to view the .dds files and change them one at a time. I don't recall if you need to install something to help you open .dds files.
If you have the leixia model, practice changing that one because they are standard png files and they are already named to whichever part they are.
For the more compilicated (and higher quality) models, i've saved a word file which compiles to each numbered .dds to correspond with whatever item part.
If you're talking about changing the colours efficiently, the hue/saturation is probably the fastest way to change 1 colour to another colour (if things are easy to group).
If the file has many different shapes, you'll have to use the replace colour feature and play with the fuzziness.
If you want to change white/blacks to a colour, use the colour balance.
If you want to change colours to white/black, just desaturate and tweak with the brightness/contrast.
As you're tweaking each file , you can hit f8 in xnalara xps to reload the texture of your model to see if the colours look right.