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