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