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