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