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