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