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)(11,12)(13,21)(14,15)(16,23)(17,18)(19,22)(20,24)(25,26,29,33)(27,31,35,30)(28,36,37,32)(34,38,40,39)(3,7)(5,8)(9,11)(10,12)(13,19)(14,17)(15,18)(16,20)(21,22)(23,24)(25,26)(27,30)(28,32)(29,33)(31,35)(34,38)(36,37)(39,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(10,15)(11,17)(16,21)(19,24)(25,27,29,35)(26,30,33,31)(28,34,37,40)(32,38,36,39)(9,12)(10,11)(13,22)(14,18)(15,17)(16,24)(19,21)(20,23)(25,26)(27,30)(28,36)(29,33)(31,35)(32,37)(34,39)(38,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,10)(11,18)(12,17)(13,16)(14,15)(19,22)(20,24)(21,23)(25,27)(26,31)(28,34)(29,35)(30,33)(32,39)(36,38)(37,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,13)(10,16)(11,19)(12,20)(14,23)(15,21)(17,24)(18,22)(25,28,29,37)(26,32,33,36)(27,34,35,40)(30,38,31,39)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.