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