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