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