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