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)(11,18)(12,16)(13,22)(14,17)(15,21)(19,24)(20,23)(25,26,30,33)(27,31,37,36)(28,29,32,39)(34,35,40,38)(9,11)(10,15)(12,19)(13,20)(14,21)(16,23)(17,18)(22,24)(25,27,30,37)(26,31,33,36)(28,38,32,35)(29,34,39,40)(2,5)(6,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,28,33,39,30,32,26,29)(27,34,31,35,37,40,36,38)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(1,3,4,7)(2,6,5,8)(11,21)(15,18)(19,20)(23,24)(25,29,26,32,30,39,33,28)(27,35,36,34,37,38,31,40)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.