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