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