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