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