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