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