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