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)(15,20)(16,22)(17,26)(18,30)(19,29)(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)(10,16,19,34,20,21,32,25)(13,28,30,26,31,23,39,40)(17,33,36,18,35,27,38,37)(2,7)(3,8)(5,6)(9,12,14,22,15,24,29,11)(10,17,19,38,20,35,32,36)(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.