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