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