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