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