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