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