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