Or, to make a repeat event, such as with the "rainbow car" vehicle spawn, you can do;
(0) Onactivate-self-firerelay
(0) onrelay-self-setcolor (red)
(100) onrelay-self-setcolor (orange)
(200) onrelay-self-setcolor (yellow)
(300) onrelay-self-setcolor (green)
(400) onrelay-self-setcolor (blue)
(500) onrelay-self-setcolor (purple)
(600) onrelay-self-firerelay
Make sure you get that last one in, or it will only do it once and stay at purple. The first number, the one that increases by 100, is the delay. That is also very important, or it will ALWAYS be purple, even if you include the last event.