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