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