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