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