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