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