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