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