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