One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4)(5,7)(6,8)(9,10)(11,12,14,18,15,17,21,24)(13,16,20,23,19,22,25,26)(4,7)(5,10)(8,9)(11,13)(12,16)(14,20)(15,19)(17,22)(18,23)(21,25)(24,26) involution — undirected(4,8)(7,9)(13,19)(16,22)(20,25)(23,26) involution — undirected(12,17)(16,22)(18,24)(23,26) 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.