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