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