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