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