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