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