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