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