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