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