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