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