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