I feel certain that Ziegler's Fig. 2.1 below (to which I assume you are referring?)
was just drawn "by hand"
in a generic drawing program,
such as Adobe Illustrator, or xfig.
(p.643 = 27th page of notes linked by Camilo)
This is probably not what you want, but Mathematica (via Combinatorica) can draw Hasse diagrams.
See, e.g., this link for how to accomplish this.
