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