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