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)(11,13,17,22)(12,16,21,23)(18,20,19,24)(25,26,31,36)(27,37,38,32)(28,30,35,33)(29,34,40,39)(1,3,5,8)(2,6,4,7)(25,27,31,38)(26,32,36,37)(28,29,35,40)(30,39,33,34)(1,4,5,2)(3,7,8,6)(10,15)(13,22)(16,23)(20,24)(27,38)(29,40)(32,37)(34,39)(9,11,14,17)(10,13,15,22)(12,19,21,18)(16,24,23,20)(25,28)(26,33)(27,29)(30,36)(31,35)(32,34)(37,39)(38,40)(9,12,14,21)(10,16,15,23)(11,18,17,19)(13,20,22,24)(25,29)(26,34)(27,35)(28,38)(30,32)(31,40)(33,37)(36,39)(9,13)(10,17)(11,15)(12,20)(14,22)(16,19)(18,23)(21,24)(25,30,31,33)(26,35,36,28)(27,39,38,34)(29,32,40,37)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.