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