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