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