Invasion's five-colored Coalition Symbol, or at least part of it, is buried in the art of most cards with the kicker ability. We'll explore the subtler ones later, but for now let's look at the most palpable examples.
The five Planeshift commons that require a land sacrifice as their kicker cost (Pollen Remedy, Falling Timber, Magma Burst, Bog Down, and Rushing River) all have their respective pieces of the symbol as a focal point of the art. (Okay, maybe Bog Down's puddle is not the focal point…).
If you didn't know to look, it might not have been obvious. But lined up side-by-side, it should be easy to see the symbol's presence.