How to use an RGB LED strip with a Vex Spike?

[Samwise_T]

My team wants to put an RGB LED strip on the robot, and we have some Vex Spike relays to use (I've heard these would work, not sure). Our LED strip has a common anode, so one wire to take an input voltage, and then one wire for each cathode of the LEDs, so one wire for red, one for blue, and one for green. Our Vex Spikes have a Voltage in, ground, and PWM input, and then a M+ and M- output. How would I wire the LED strip with one (or a few) of these relays in order to control the light color? So far I've tjougjt of using one relay per LED cathode, but I'm not sure what to do with the remaining + wire. Any help would be greatly appreciated.