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