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