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