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