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