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