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