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