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