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