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