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