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