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