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