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