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