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