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