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