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