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