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