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