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