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