This is a really good question. I suspect the color in the image has been enhanced. I've been trying to find a scientific reason that the clouds could appear blue, but haven't found anything conclusive.

However, I did find a NASA page with raw images of Jupiter.

Here's a raw image:

Here's an image that's been color-enhanced:

It's not uncommon for space images to be color-enhanced. On the one hand, it may feel less authentic. On the other hand, the visible light levels in space may be insufficient for our expectations and uses anyway. Although I don't know the origin of the picture at the top of this page, I know that it's common practice for space photos to be enhanced. In fact they're often taken in non-visible spectrums and fully converted to something humans can see and comprehend. Ever see detailed, colorful photos of galaxies? They were probably taken in X-ray and colorized in processing. Cool as it would be, you wouldn't see those colors in real life.