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