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