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