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