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