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