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