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