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