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