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