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