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