One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(9,10)(11,18)(12,16)(13,22)(14,19)(15,20)(17,21)(23,24)(25,26)(27,30)(28,31)(29,32)(33,38)(34,37)(35,39)(36,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,11)(10,14)(12,19)(13,20)(15,17)(16,18)(21,23)(22,24)(25,27)(26,30)(28,33)(29,34)(31,38)(32,37)(35,40)(36,39)(9,11)(10,15)(12,19)(13,23)(14,17)(16,24)(18,22)(20,21)(25,28,29,35)(26,31,32,39)(27,33,34,40)(30,36,37,38)(2,6)(5,7)(10,16)(11,19)(17,22)(20,23) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.