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