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