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