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