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