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