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