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