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