The image was created by David Bachman (Pitzer College), Saul Schleimer (University of Warwick) and Henry Segerman (Oklahoma State University).
They explain it as being the "view" inside of a finite-volume hyperbolic three-manifold. The three-manifold contains a surface; when a “light ray” leaves your eye it becomes darker when it crosses the surface in the positive sense and lighter when it crosses in the negative sense. The elaborate patterns come from the complicated geometry and topology of the ambient three-manifold.
We used the images for banner stands for the recent Maths Open Day.