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