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