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