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)(11,17)(12,16)(13,14)(15,18)(19,23)(20,21)(22,24)(25,26,30,31)(27,29,34,32)(28,33,36,38)(35,37,40,39)(1,3,5,8)(2,6,7,4)(10,14)(15,17)(16,21)(22,23)(26,31)(28,36)(29,32)(35,40)(1,2)(3,4)(5,7)(6,8)(11,18)(12,20)(15,17)(16,21)(26,31)(27,34)(28,36)(37,39) involution — undirected(1,4)(2,3)(5,6)(7,8)(9,11,13,18)(10,15,14,17)(12,19,20,24)(16,22,21,23)(25,27)(26,32)(28,35)(29,31)(30,34)(33,39)(36,40)(37,38)(1,3)(2,4)(5,8)(6,7)(9,12,13,20)(10,16,14,21)(11,19,18,24)(15,22,17,23)(25,28)(26,33)(27,35)(29,37)(30,36)(31,38)(32,39)(34,40)(1,4)(2,3)(5,6)(7,8)(9,10)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,29,30,32)(26,27,31,34)(28,37,36,39)(33,35,38,40)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.