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