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