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