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