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