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