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