The dots always represent the number of cross terms the group costs to use as a support. If the group is being used as support, the dots will be on the left, on the support range indicator (between the handles if they are visible). If it is not, they will be on the right in a small frame.
Different colours indicate that the cross terms come from different pools. This can happen if the device has multiple DSPs, in which case there will be two indicators showing how many cross terms are being used (e.g. a blue "53 of 96 used" and a red "72 of 96 used").
However, it can also happen if some speakers are excluded from being used as support speakers. In that case they will be represented as different coloured dots, but there will not be a matching indicator showing how many cross terms are available for that colour, because they are considered to belong to a virtual DSP that has 0 available cross terms, which prevents you from using them as supports