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