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)(25,26,30,35)(27,37,28,32)(29,36,31,34)(33,38,40,39)(1,3,4,8)(2,5,6,7)(11,19)(15,23)(18,24)(20,22)(25,27,31,38,30,28,29,39)(26,32,34,33,35,37,36,40)(9,11,14,19)(10,15,17,23)(12,20,13,22)(16,24,21,18)(25,28)(26,33)(27,30)(29,39)(31,38)(32,34)(35,40)(36,37)(2,6)(5,7)(9,12,14,13)(10,16,17,21)(11,20,19,22)(15,24,23,18)(25,29,30,31)(26,34,35,36)(27,38,28,39)(32,40,37,33)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.