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