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