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