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