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