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)(15,22)(16,27)(17,28)(18,25)(19,24)(20,23)(21,26) involution — undirected(1,2)(3,4)(6,10)(11,12)(13,15)(14,21)(16,20)(17,18)(19,26)(22,24)(23,28)(25,27) involution — undirected(5,7,9,8)(6,11,10,12)(13,16,20,15,19,17,18,26)(14,22,25,27,24,21,23,28)(2,4)(5,8,9,7)(6,12,10,11)(13,17,18,15,19,16,20,26)(14,21,23,27,24,22,25,28)(6,10)(11,12)(13,18,19,20)(14,23,24,25)(15,17,26,16)(21,28,22,27)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.