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