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