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