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