Involves Selective coloring and Vibrance or Hue/Saturation
01. Duplicate the base and set it to Screen 100%, this will make it brighter.
02. Press crtl+alt+shift+e to stamp all layers, then go to Filter>>Gaussian Blur and choose Radius 7,0. Set this layer to Soft Light 100%, this will make the colors more colorful and also add more contrast.
03. Make a new Selective Coloring layer with these settings:
REDS: +43, +80, -72, 0
YELLOWS: +50, +79, -84, 0
This will make the icon very purple/pink-ish, and it's supposed to look exaggerated.
04. Another Selective Coloring layer:
REDS: 0, 0, +100, 0
YELLOWS: 0, 0, +100, 0
NEUTRALS: 0, 0, +58, 0
Now the icon looks very colorful, which is the look we are going for here.
05. Now, select both the Selective Coloring layers by holding in ctrl and clicking on both. Right-click on the layers and duplicate them. Now we are making the SC layer having a bigger effect.
06. Now add this texture by aquatilitis and set it to Soft Light 100%, this will make it more green-yellow-ish.
07. Now make a new Vibrance layer, with these settings:
A new Hue/Saturation layer with these settings:
And you're done!
PS: This coloring most likely have to be toned down a bit for use in screencaps of real people.
Other examples with similar coloring method: