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