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