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