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