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