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)(15,19)(16,20)(17,18)(22,26)(24,28) involution — undirected(1,2,3,4)(6,7)(8,12)(13,15,17,20)(14,16,18,19)(22,26)(23,27)(6,7)(10,11)(14,18)(15,20)(21,22,25,26)(23,24,27,28)(5,7,9,6)(8,11,12,10)(13,15)(14,16)(17,20)(18,19)(21,23,25,27)(22,24,26,28)(5,8)(6,10)(7,11)(9,12)(13,16)(14,15)(17,19)(18,20)(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.