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