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)(11,14)(12,13)(15,16)(17,18,21,19)(20,23,24,22)(25,26,29,32)(27,30,33,37)(28,35,36,31)(34,40,39,38)(3,7)(5,8)(10,13)(11,15)(17,19,21,18)(20,23,24,22)(27,33)(30,37)(34,39)(38,40)(1,2,4,6)(3,5,7,8)(9,10)(11,16)(12,13)(14,15)(25,27)(26,30)(28,34)(29,33)(31,38)(32,37)(35,40)(36,39)(1,2)(3,5)(4,6)(7,8)(17,20)(18,22)(19,23)(21,24)(25,28,29,36)(26,31,32,35)(27,34,33,39)(30,38,37,40)(1,3)(2,5)(4,7)(6,8)(9,11,12,15)(10,14,13,16)(25,26)(27,30)(28,31)(29,32)(33,37)(34,38)(35,36)(39,40)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.