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