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)(13,14,16,17)(15,19,20,18)(21,22,25,26)(23,24,28,27)(6,9)(10,11)(14,17)(18,19)(22,26)(23,28) involution — undirected(13,15)(14,18)(16,20)(17,19)(21,23,25,28)(22,27,26,24)(1,2)(3,4)(5,7,8,12)(6,10,9,11)(13,15)(14,19)(16,20)(17,18)(21,24)(22,23)(25,27)(26,28)(5,6)(7,11)(8,9)(10,12)(13,14)(15,18)(16,17)(19,20)(21,22)(23,27)(24,28)(25,26) 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.