Well Japanese astronaut and mother, Naoko Yamazaki, currently floating approximately 350km above us on the International Space Station (ISS) decided to keep a promise that she made to her 7 year old daughter, and demonstrated how to make a coloured bubble!
Mixing some red tropical fruit juice with liquid soap, she produced shiny red bubbles in Space, much to the delight of her daughter and husband who were watching back home via a video phone.
Adding a coloured dye to bubble mixtures on Earth does not produce coloured bubbles as the dye attaches to the water molecules and not to the surfactant (surface active agent - the soapy bit!). This means that when a bubble is blown, the dye falls to a point at the base leaving a clear bubble. The experiment worked in Space because the zero-gravity environment on the ISS allowed the colour pigment to spread around the bubble rather than fall to the bottom.
The rainbow colours that can sometimes be seen in a bubble are actually created by interfering light waves caused by the reflection of light from the inner and from the outer surfaces of the bubble.