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