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