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