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)(11,13)(12,16)(14,15)(17,21)(18,20)(19,22)(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)(9,11,14,17)(10,13,15,21)(12,18,19,23)(16,20,22,24)(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)(10,16)(11,18)(13,20)(14,19)(15,22)(17,23)(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)(10,17)(11,15)(12,20)(14,21)(16,23)(18,22)(19,24)(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.