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