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