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