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