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