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