You cannot change the colour of the keyboard. However, there are 3 different colours to buy: blue, green and red. Digitec only seems to have the blue version in stock at the moment. Here are the model numbers:
SGB-3010-KKMF1 (Blue backlit version)
SGB-3011-KKMF1 (Red backlit version)
SGB-3012-KKMF1 (Green backlit version)