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