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