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