Create new file (CTRL + N).Make sure you have default colors selected(key D). Filter -> Render -> Clouds.
Filter -> Render -> Difference Clouds:
Adjustments -> Levels (CTRL + L). Adjust levels to something similar to this:
My result is this:
If you want to color this texture, use Adjustments -> Hue/Saturation (CTRL + U). Colorize must be selected. Here is what it might look like.