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