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