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