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