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