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