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