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