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