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