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