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