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