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