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