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)(11,17)(12,20)(13,19)(14,18)(15,21)(16,22)(23,24)(25,26)(27,37)(28,40)(29,30)(31,34)(32,36)(33,39)(35,38)(1,3,5,8)(2,6,4,7)(9,11)(10,17)(12,13)(14,23)(15,22)(16,21)(18,24)(19,20)(25,27,32,39)(26,33,36,37)(28,38,31,30)(29,34,35,40)(9,12,16,14)(10,18,22,20)(11,23,21,13)(15,24,17,19)(25,28,32,31)(26,34,36,40)(27,38,39,30)(29,33,35,37)(9,13,16,23)(10,19,22,24)(11,12,21,14)(15,18,17,20)(25,29,32,35)(26,30,36,38)(27,34,39,40)(28,37,31,33)(1,2,5,4)(3,6,8,7)(9,14,16,12)(10,20,22,18)(11,23,21,13)(15,24,17,19)(25,30)(26,35)(27,28)(29,36)(31,39)(32,38)(33,40)(34,37)(1,4,5,2)(3,7,8,6)(9,15)(10,21)(11,22)(12,24)(13,18)(14,19)(16,17)(20,23)(25,31,32,28)(26,34,36,40)(27,30,39,38)(29,33,35,37)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.