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