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