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