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