Currently, the Bubble View on WDQS always automatically chooses the color based on the node name (out of the 20-color scale [d3.scale.category20c](https://github.com/d3/d3/wiki/Ordinal-Scales#category20c)). We could also use one of the result columns to let the query author explicitly specify the color of a bubble.
I have a patch for this that uses the color from the ?rgb column (if present) as RGB color, which I’m about to upload to Gerrit, but I figure that the discussion of this feature belongs here and not on code review.
Note that this feature is not limited to items that have some color statement; with BIND forms, you can also explicitly color-code arbitrary results.
Example queries: political parties with membership and color, countries with population color-coded by continent