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