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