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