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