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