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