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