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