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