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