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)(14,20)(16,21)(23,28)(24,27) involution — undirected(5,7,9,8)(6,10,11,12)(13,14)(15,24)(16,26)(17,23)(18,20)(19,28)(21,22)(25,27)(1,2,3,4)(13,15,18,25)(14,21,20,16)(17,22,19,26)(23,27,28,24)(5,8,9,7)(6,10,11,12)(13,16)(14,22)(15,23)(17,27)(18,21)(19,24)(20,26)(25,28)(13,17)(15,22)(18,19)(23,28)(24,27)(25,26) 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.