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