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