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