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