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