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