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