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