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