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