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