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