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