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