Yes, if one doesn't want to go with a clear cover to have sunlight heat the pool (but at the cost of having more chlorine degrade from sunlight), then the next best choice for heating is a dark cover (such as black). However, the ideal for a black cover is for the underside (i.e. bubble-tops) to be black but for the top size (i.e. the flat side) to be clear. This way the hot flat side doesn't have to try and get its heat through the air pockets in the bubbles.
Heating the surface water isn't efficient so if you can point the returns slightly upwards to create a greater surface flow that even "bounces" off the cover, then that would work better. However, one also wants circulation to the bottom so there's really not a great option here unless one has enough returns to have some pointing slightly upward and others pointing downward for a rolling flow pattern.
In my own pool, I have an electric safety cover that is relatively thin (i.e. it's not a bubble-type cover) and I noticed that changing the color from a light tan to a dark blue has increased heating, but only a little bit. Black would heat more since even dark blue reflects a goodly amount of heat.