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