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