One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,6)(7,8)(9,10)(11,18)(12,16)(13,21)(14,17)(15,19)(20,23)(22,24)(25,26)(27,30)(28,31)(29,32)(33,39)(34,37)(35,38)(36,40) involution — undirected(1,2,4,5)(3,6,7,8)(9,11)(10,15)(12,19)(13,22)(14,20)(16,23)(17,24)(18,21)(25,27)(26,30)(28,33)(29,34)(31,36)(32,37)(35,40)(38,39)(1,3)(2,6)(4,7)(5,8)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,24,18)(25,28)(26,31)(27,33)(29,35)(30,36)(32,38)(34,40)(37,39)(10,17)(15,24)(16,21)(18,23)(26,32)(27,34)(31,38)(33,40) 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.