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