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