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