... Apply Colours to Emitters?

A “RealFlow Particle Importer” plugin can only handle one particle sequence at a time. If you want to import more sequences you need an appropriate number of plugin nodes. By default, the particles are displayed as small white crosses. In order to apply different colours to separate them visually please follow these steps – of course this workflow can also be used with a single plugin: 

1. Simulate > Thinking Particles > Thinking Particle Settings…
2. Expand the “All” branch inside the “Particle Groups” area.
3. Click on the white rectangles next to an emitter sequence and define a new color.

The colour is only visible in the viewport, not in the render. To change the colour for the render, simply apply a material.