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