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