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)(17,18,20,22)(19,21,23,24)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(9,11,14,13)(10,15,12,16)(19,23)(21,24)(26,27)(29,37)(31,33)(35,40)(2,6)(3,8)(9,11,14,13)(10,16,12,15)(17,19,20,23)(18,21,22,24)(25,27,30,26)(28,33,36,31)(29,34,37,32)(35,39,40,38)(1,3,5,8)(2,7,6,4)(9,12,14,10)(11,16,13,15)(25,28,30,36)(26,31,27,33)(29,35,37,40)(32,38,34,39)(1,4,5,7)(2,8,6,3)(9,13,14,11)(10,16,12,15)(17,18)(19,21)(20,22)(23,24)(25,29)(26,32)(27,34)(28,35)(30,37)(31,38)(33,39)(36,40)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.