The Cubic Graph is a higher dimensional version of The Grid, and it contains itself in the same way The Grid does, and all other examples of the berry paradox. The z axis line is what holds all of the y axis and x axis lines together.
Unlike the grid, the blank spaces here actually mean something completely different. The blank spaces don't represent 3d versions of The Grid's Nothingness, but it actually represents TV static (except for one plane of the blank space). It is the place where TV static combines into the ultimate blank spaces that are bigger and bigger. The largest layer of blank space is called The Ultimate Television.