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