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