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