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)(27,35)(28,34)(29,38)(30,36)(31,32)(33,37)(39,40)(3,7)(5,8)(9,11,13,19)(10,14,16,17)(12,18,21,24)(15,22,20,23)(25,27,30,31)(26,32,36,35)(28,37,29,39)(33,34,40,38)(1,3)(2,5)(4,7)(6,8)(12,21)(15,20)(18,24)(22,23)(25,28)(26,33)(27,37)(29,30)(31,39)(32,34)(35,38)(36,40) involution — undirected(3,7)(5,8)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(25,29,30,28)(26,34,36,38)(27,37,31,39)(32,33,35,40)(2,6)(5,8)(10,16)(14,17)(15,20)(22,23)(25,27,30,31)(26,35,36,32)(28,37,29,39)(33,38,40,34)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.