The flesh coloured gimmick is your secret weapon to making the silks change colour. Begin by secretly loading one of the coloured hankies into the flesh coloured gimmick. Make sure the corner of one of the silks is accessible from the bottom of the gimmick.
BEGIN THE PRESENTATION - The flesh coloured gimmick (tube) is worn on the middle finger of your right or left hand. With this hand also you hold the other coloured hanky waving in the air and keeping you hand moving at all times. As you begin the trick you load the flesh coloured tube into your other hand (clenched fist) and then push the other hanky into the fist. The hanky is not going into your exact fist - it goes into the flesh tube - pushing the other colour out.
Done smoothly the tube can then be stolen again onto your middle finger. You can open your hands to show the hanky has actually changed colour. See the video below for some ideas on presentation.