You cannot colour a preset in with the game's colours/markings. You will need a program like Gimp, photoshop ect. Paint will not work. When you colour in the preset in one of the drawing programs you will have to save it in one of the preset folders. (I would recommend keeping folder 11 & 12 untouched since they already have two starting presets)
If you are not sure on how to make a preset there is a very good set of tutorials made by WhisperingWaves. You should check it out if you have any problems.;
http://www.feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=47969.0 (http://www.feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=47969.0)
Hope that helped. C'ya! c: