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