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