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