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