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