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