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