Okay, there's clearly a bit of confusion here. Firstly, let's consider the situation without advanced warp sensors.
The AI initiates warp gate waves against planets you control. You control a planet if you have a completed command station there. The AI can only initiate a wave against a given planet if it controls a warp gate on an adjacent planet. When the wave is initiated, a timer will start counting down, stating which planet the wave is heading for. Upon the timer reaching 0, a wave of AI ships will spawn on your planet from the wormhole that leads to the planet with the AI warp gate that initiated the wave.
Now, let's say there is more than one AI planet with a warp gate connected to you. A wave timer may start counting down, but you have no idea which AI planet initiated the wave, so you don't know which wormhole the AI ships will come through.
If you have an advanced warp sensor on the planet, the wormhole that is about to spew forth the AI ships will turn orange, letting you know where they'll come from.
Hope this helps.