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