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