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