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