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