Ok, assuming we did both get the same map, your red clay is at the following locations.
-32, 106, -47 (Under a layer of dirt, so its not visible)
-90, 115, -61 (Mostly under a layer of dirt, but there is a few blocks above ground.) This one is by far the largest deposit of clay.
It does happen that the clay spawns with a layer or 2 of dirt, sand or gravel above it (red and blue).