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