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