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