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