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