you can only support max 4 colors so you may want to do
colors[0] = "1 0 0 1";
colors[1] = "0 1 0 1";
colors[2] = "0 0 1 1";
colors[3] = "1 0 0 1";
so that it transitions fine if you spawn one every time the last particle disappears (eg eject period same length as lifetime of particle)