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