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