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