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