When you start the game, go to
Career, you'll than have to buy a car for your first event.
After you bought the car the trophy will pop
Also an opportunity to get the following trophy:
Screenshots are from the Xbox since I only have the Xbox version but I imagine the solution is the same here, just the
button instead of the
button.
After you buy your car, press
to go to livery.
Press
again to customise that livery.
When you select a different color the trophy will pop