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