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