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