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