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