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