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