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)(11,18)(12,16)(13,22)(14,17)(15,20)(19,24)(21,23)(25,26,31,35,30,32,29,34)(27,36,38,39,37,33,40,28)(1,3,4,7)(2,5,6,8)(9,11,14,20)(10,15,17,18)(12,19,13,21)(16,23,22,24)(26,32)(27,37)(34,35)(38,40)(2,6)(3,7)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,27,30,37)(26,33,32,36)(28,34,39,35)(29,40,31,38)(2,6)(5,8)(11,20)(15,18)(19,21)(23,24)(25,28,31,36,30,39,29,33)(26,27,35,38,32,37,34,40)(9,13,14,12)(10,16,17,22)(11,21,20,19)(15,23,18,24)(25,29,30,31)(26,34,32,35)(27,38,37,40)(28,36,39,33)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.