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