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