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