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