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