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