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