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