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