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