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