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