The color is based on the stock price as per my response earlier which I have appended below, the reason for the same is volume bar coloured green/red by the volume in the candle does not signify much as the height of the volume bar itself signifies that.
Lakshmikanth_Jadhav
Incorrect @Srinivas, the latest red volume bar means that the close/LTP price of this candle is less than the close of the previous candle. And the latest green volume bar means that the close/LTP price of this candle is more/equal to the close of the previous candle.