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