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