The Outer Layer is an extremely unknown and maybe theoretical area/border separating The Cluster and The Far. Since this layer is theoretical, no real description or picture of it can be shown. The picture is just a representation of The Outer Layer, and is most likely not what it actually looks like.
This extra layer was first proposed in 2738 OYC, when a huge telescope detected an unknown force/"thing" traveling at speeds unheard of way outside of the known borders of The Cluster's Final Layer.
Creatures are still wondering who first decided to call it an "extra layer" rather than a whole new verse/container.