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