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