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