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