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