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