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