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