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