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