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