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