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