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