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