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