What is this stick diagram?

This is a picture of the partially ordered set of special nilpotent orbits for the rank 8 exceptional Lie algebra g. Whereas there are 70 nilpotent orbits in g, only 46 of these are special. The "red dot" distinguishes the unique nilpotent orbit in g with fundamental group the symmetric group of 5 letters. This particular nilpotent orbit has been referred to as "...the most complicated example in the world..."