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