So this is a picture with a blue spiral and a green spiral, right? Not so fast, Eagle-eye. Get in close and you will see that the blue and the green are actually the same color.
The reason they look like different colors, explains Bad Astronomy, is because our brain judges the color of an object by comparing it to surrounding colors. In this case, the stripes are not continuous as they appear at first glance. The orange stripes don’t go through the "blue" spiral, and the magenta ones don’t go through the "green" one. Here’s a zoom to make this more clear: