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