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