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