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