Color is sent in a color burst at the end of each line
Color is amplitude modulated on the frequency modulated intensity signal
Explication
Analog SSTV has no colour subcarrier and no colour burst; instead the separate colour components of each picture line are sent one after another as their own scan lines, and the receiving software reassembles them. Any colour information carried on a subcarrier would not fit in the narrow audio channel SSTV uses.