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