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)(11,17)(12,25,28,18)(13,29)(14,21)(15,31)(16,20)(19,24)(22,35,38,32)(23,33)(26,40,39,34)(27,37,30,36)(2,5)(6,8)(9,11,14,23,16,24,15,13)(10,17,21,33,20,19,31,29)(12,26,27,38,28,39,30,22)(18,34,36,35,25,40,37,32)(1,3,4,7)(2,6,5,8)(9,12)(10,18)(11,22)(13,26)(14,30)(15,27)(16,28)(17,32)(19,35)(20,25)(21,37)(23,39)(24,38)(29,34)(31,36)(33,40)(3,7)(6,8)(9,13,15,24,16,23,14,11)(10,19,21,29,20,17,31,33)(12,26,27,38,28,39,30,22)(18,35,37,34,25,32,36,40)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.