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