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