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