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