One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,3)(4,7,8,6)(9,10,14,15)(11,13,17,21)(12,16,19,22)(18,20,23,24)(25,26)(27,32)(28,33)(29,39)(30,31)(34,40)(35,38)(36,37)(2,3)(6,7)(12,19)(16,22)(18,23)(20,24)(26,31)(28,37)(32,38)(34,39) involution — undirected(1,3,5,2)(4,7,8,6)(10,15)(11,17)(16,22)(18,23)(26,31)(27,35)(33,36)(34,39)(1,4)(2,6)(3,7)(5,8)(9,11)(10,13)(12,18)(14,17)(15,21)(16,20)(19,23)(22,24)(25,27)(26,32)(28,34)(29,36)(30,35)(31,38)(33,40)(37,39) involution — undirected(9,12)(10,16)(11,18)(13,20)(14,19)(15,22)(17,23)(21,24)(25,28,30,37)(26,33,31,36)(27,34,35,39)(29,32,40,38)(9,13)(10,11)(12,20)(14,21)(15,17)(16,18)(19,24)(22,23)(25,29,30,40)(26,34,31,39)(27,36,35,33)(28,38,37,32)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.