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