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)(11,22,26,36)(12,27,31,39)(13,32)(14,20)(15,21)(16,24,37,25)(17,30,40,29)(18,34)(19,33)(23,38)(28,35)(1,2)(3,7)(4,6)(5,8)(9,11)(10,16)(12,28)(13,29)(14,25)(15,26)(17,38)(18,39)(19,22)(20,36)(21,37)(23,31)(24,33)(27,32)(30,34)(35,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,12)(10,17)(11,23)(13,24)(14,29)(15,31)(16,35)(18,22)(19,27)(20,39)(21,40)(25,34)(26,28)(30,33)(32,36)(37,38)(3,8)(5,7)(9,13,33,23,15,34,14,28)(10,18,19,35,21,32,20,38)(11,12,25,30,26,31,24,29)(16,17,36,27,37,40,22,39)(2,6)(5,7)(9,14,15,33)(10,19,21,20)(11,24,26,25)(12,29,31,30)(13,28,34,23)(16,36,37,22)(17,27,40,39)(18,35,32,38)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.