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