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