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