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