Yes, the colour of any given spoils is random. However, in the true CC spirit, you can always play with the figures
. e.g. if you hold on to your spoils until you have 5 and have to cash, you can try to play for a set you like.
Say you have three spoils all red. You don't need to cash,this turn, you can take the deploy and hope to get a blue and green spoils soon, for a rainbow set- You are guaranteed to have a red set to cash some time, have some chance of getting a rainbow set you can cash instead of the possible red set and have no chance to get a three green or a thee blue set, this go
If you have three red spools- the odds are 2/3 your fourth spoil will be blue or green. IF your fourth spoils is blue or green, there is one chance in 3 the fifth spoils will make a rainbow set. Starting with 3 red spoils, the odds are 2/9 of getting a rainbow set, this go.
Of course if you have three red and get a fourth spoil red. there is zero chance of getting anything other than a red set this go. Only question is : do you cash in a red set next round or the round after.
A factor to consider that may affect your play, for good or evil, is the 2 auto -deploy for cashing a spoils and you hold the tert. Say one of your three red spoils is Perth and you hold Perth now or could take it easily. Cashing the set combo for what it is worth and the 2 auto deploy may be something to think about.
Of course in escalating sets, any change in value is based on others cashing sets, not on the colour of your spoils, but I will shut up now and let the Fun with Figures types have a say.