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