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