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