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