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