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