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