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