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